Commercial products containing a dilute aqueous solution of sodium silicate and flocculated copper metal have been successful in the automotive industry in the sealing of cracks in internal combustion engine cooling systems, including engine blocks, radiators, head gaskets, heads, heater cores, hose connections, and freeze plugs. After introduction of the product into the cooling system, the aqueous solution containing the sodium silicate seeps through the crack as the flocculated copper bridges the crack at its narrowest point. Flow of the aqueous solution through the crack is thereby decreased. Atmospheric oxygen, coupled with the heat transferred through the suspended copper, causes solidification of the sodium silicate in the crack to a hard crystalline material resembling glass; hence, the aqueous solution is often referred to as “liquid glass.”
Such commercial products were developed when automotive coolants were alcohol based and gained immense popularity since they were highly compatible with such alcohol based coolants. Today, however, most coolant systems are glycol based, principally mixtures of ethylene glycol and/or propylene glycol and water. Unfortunately, when an aqueous solution of sodium silicate, containing sufficient sodium silicate to function effectively as a sealant, is poured into a cooling system comprised of significant concentrations of ethylene and/or propylene glycol, the sodium silicate frequently forms an insoluble precipitate. Such precipitates typically plug small orifices in cooling systems, thereby resulting in restricted coolant flow and engine overheating.
In order to address the problems caused by the incompatibility of such commercial products with glycol-based coolants, suppliers typically advise consumers to first flush the cooling system with water in order to remove ethylene glycol (and/or propylene glycol) prior to addition of the aqueous sodium silicate solution to the cooling system. Such flushing presents a major inconvenience to consumers and presents a serious drawback to the desirability of use of the product.
Methods of sealing cracks in cooling systems employing sodium silicate are desired which will render moot the requirement of flushing the cooling system with water prior to the addition of the sodium silicate.